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authorNeilBrown <neilb@suse.de>2010-05-22 08:31:36 +1000
committerNeilBrown <neilb@suse.de>2010-05-22 08:31:36 +1000
commit19fdb9eefb21b72edbc365b838502780c392bad6 (patch)
treedeae04c48532d6eab64ed4b0396737bb854b5506 /Documentation/sound/alsa/HD-Audio.txt
parentbe6800a73aa2f3dc14744c3b80e676d189789f04 (diff)
parent3ff195b011d7decf501a4d55aeed312731094796 (diff)
Merge commit '3ff195b011d7decf501a4d55aeed312731094796' into for-linus
Conflicts: drivers/md/md.c - Resolved conflict in md_update_sb - Added extra 'NULL' arg to new instance of sysfs_get_dirent. Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'Documentation/sound/alsa/HD-Audio.txt')
-rw-r--r--Documentation/sound/alsa/HD-Audio.txt20
1 files changed, 15 insertions, 5 deletions
diff --git a/Documentation/sound/alsa/HD-Audio.txt b/Documentation/sound/alsa/HD-Audio.txt
index f4dd3bf99d1..bdafdbd3256 100644
--- a/Documentation/sound/alsa/HD-Audio.txt
+++ b/Documentation/sound/alsa/HD-Audio.txt
@@ -119,10 +119,18 @@ the codec slots 0 and 1 no matter what the hardware reports.
Interrupt Handling
~~~~~~~~~~~~~~~~~~
-In rare but some cases, the interrupt isn't properly handled as
-default. You would notice this by the DMA transfer error reported by
-ALSA PCM core, for example. Using MSI might help in such a case.
-Pass `enable_msi=1` option for enabling MSI.
+HD-audio driver uses MSI as default (if available) since 2.6.33
+kernel as MSI works better on some machines, and in general, it's
+better for performance. However, Nvidia controllers showed bad
+regressions with MSI (especially in a combination with AMD chipset),
+thus we disabled MSI for them.
+
+There seem also still other devices that don't work with MSI. If you
+see a regression wrt the sound quality (stuttering, etc) or a lock-up
+in the recent kernel, try to pass `enable_msi=0` option to disable
+MSI. If it works, you can add the known bad device to the blacklist
+defined in hda_intel.c. In such a case, please report and give the
+patch back to the upstream developer.
HD-AUDIO CODEC
@@ -196,7 +204,6 @@ generic parser regardless of the codec. Usually the codec-specific
parser is much better than the generic parser (as now). Thus this
option is more about the debugging purpose.
-
Speaker and Headphone Output
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
One of the most frequent (and obvious) bugs with HD-audio is the
@@ -592,6 +599,9 @@ probing, the proc file is available, so you can get the raw codec
information before modified by the driver. Of course, the driver
isn't usable with `probe_only=1`. But you can continue the
configuration via hwdep sysfs file if hda-reconfig option is enabled.
+Using `probe_only` mask 2 skips the reset of HDA codecs (use
+`probe_only=3` as module option). The hwdep interface can be used
+to determine the BIOS codec initialization.
hda-verb